An image forming apparatus is an apparatus to print an image on a printing medium, for example, sheet(s) of paper, according to input image signals. Non-limiting examples of the image forming apparatus may include, e.g., printers, copiers, facsimiles, devices combining one or more functions of the foregoing devices, and the like.
An electro-photographic type image forming apparatus, as a non-limiting example of an image forming apparatus, includes an exposing unit, an image carrier, a developing unit, etc. The exposing unit irradiates light to the image carrier charged with a predetermined electric potential, to form an electrostatic latent image on a surface of the image carrier. The developing unit feeds developer, e.g., toner, to the image carrier, on which the electrostatic latent image is formed, to form a visible image. Once formed, the visible image is transferred from the image carrier onto a printing medium, and is fixed on the printing medium, thus completing the printing of the image.
The image forming apparatus may be classified, on the basis of a printing method, into a multi-pass type and a single-pass type. The multi-pass type has a simple configuration and can achieve a reduced product size, but suffers from a slower printing speed in the case of color printing because it must sequentially repeat the transfer of developer as many times as the number of developer colors being employed. On the other hand, a single-pass type, which is also often referred to as a tandem type, transfers different colors of developers simultaneously, and thus can maintain the same printing speed as black-and-white printing even in the case of color printing. A tandem type image forming apparatus however must include essentially the same number of components associated with the developing an image, such as, e.g., an exposing unit, image carrier and developing unit, as the number of developer of different color being employed in order to transfer developers simultaneously.
Due to the volume of the many exposing unit and the corresponding number of image carriers, the conventional image forming apparatus has an increased overall product size. The conventional image forming apparatus further has an increased overall height because the exposing unit is typically arranged in the lower region of the image forming apparatus, where, for example, a paper feeding device to store and feed printing media is also arranged. This arrangement makes it difficult to design the exposing unit so as not to interfere with the paper feeding device, etc. Furthermore, even if the exposing unit is designed to be sufficiently spaced apart from the paper feeding device, for example, to avoid interferences therebewteen during operation, this may result in a less efficient space utilization. Improved space utilization in image forming apparatuses is thus desirable.